Apparatus for the remote control of a tunable radio frequency converting system



Feb, 13, 1951 H B. R. BOOSMAN ET AL. 2,541,329

APPARATUS FOR THE REMOTE CONTROL OF A TUNABLE RADIO FREQUENCY CONVERTING SYSTEM Filed July 20, 1946 A R-F AMPLIFIER HEI'ERODYNE l-F AMP AUDIO AND J 0 CIRCUIT DETECTOR AMPUFIER w L LOCAL OSCILLATIONS AUXILIARY l OSCILLATOR l2 "ll FREQUENCY DISCRIMINATOR I l l l CONTROL [OSCILLATOR LOUD SPEAKER CONTROL DEVICE INVENTORS HERMAN BERNARD RUDOLF BOOSMAN EDUARD HERMAN HUGENHOLTZ AGENT Patented Feb. 13, 1951 'APPA-RATUS FOR THE REMOTE CONTROL OFA TUNABLE RADIO FREQUENCY ooN- "VERTING SYSTEM Herman BernardBndolf. Boosman and Eduard 'Herman Hugenholtz, Eindhoven, Netherlands, jassignors to Hartford National Bank and Trust Company, Hartford, Conm, as trustee Application' July 20, 1946,;.;Serial No.'585 ,125

In the Netherlands July 9,- 1943 Sectionl, Public Law 590, August 8, 1946 Patent expires July 9, 1963 5- 54 C a s- Thisinvention relatesto an apparatus tunable from a remote point of control, and more-particularly'to a radio transmitter or receiven-whose .tuning frequency is determined 'by-the frequency of at least one oscillator.

For the remote, control of apparatus 'Whose tuning'frequency is determined "by the frequency -'of an oscillator; it lSTkIlOWIYtO adjust the oscilla- :-such manner that an oscillation obtained by ztgmi-xing the frequenciesflgenerated by the said mQSCi-llators determines the, tuning frequency of the apparatus.

, The arrangement described offers theladvantage that the fine tuning of theapparatus ob- -tained by means ofthe continuously vadjustable oscillator follows immediately, without delay,

tor fromzthe point of control of the apparatus after the adjustment of the correspondingmemiand to make non-resonant" any additional cir- 1Q; her for the remote'control, for if this fine adjust- .t'cuits not pertaining to the'o'scillator, 'sothat they :ment is effected byv means of any of the usual synced-not be" tuned. methodsof remote control, there-alwayselapses Alsoin those casesin which for thelsaidoscil- -a certain;period of time-between the adjustment latory circuits the frequen'cyazbands into which of the remote control memberand theinstant at "'T1fth"WhO1e 10f; the frequency range to be covered -5: :which the member for the fine tuning of: the apissubdivided, should be chosen-diiierentfrom paratus attains the position which corresponds 7. those for the said oscillator, as, for example, is tothe chosen adjustment: When tuningtranssometimes; the casewwith-direction-finding remit ters and receiversaespecially direction find ceivers, the tuningof' the circuits not pertaining ing receivers to which the invention applies to the oscillator has-hitherto been'omitted. 2 1 1 p iG yS -C t delay is extr mely Thisinvention provides'means with the aid of troublesome, so that rapid as. w e 1l as exact tunwhich all the-tunable oscillatory-circuitscan be ing becomes quite-impossible.

tuned from a distance'in-a simple manner. --The, firstvauxiliary oscillation is preferably According to; the :invention, the :oscillator fretaken from any of the said'oseillators or obtained "quency. is adjustedfrom the remote point of con- 2 by mixing oscillations 'generated by these oscilla- Jtrol; While an auxiliary-: oscillationwhose; fre- .tors.

' quency'isdetermined"by theoscillatorfrequencx The adjustment of the said oscillatory circuits brings the: tuning-frequencyioftheasaid oscillais preferably efiected in such-manner that the 'torycircuits into correspondencewiththe ad- H tuning is always varied until the twoauxiliary j ted Osc o que y' ea s Of-a-ireso oscillations exhibit a fixed frequency difference, quency detector. iwhich difference ischosen in such-manner that To the frequency detector -ispreferably sup- 5, the secondauxiliary oscillation cannot give-rise plied, in addition, a: second auxiliary oscillation 1-,to, the production of a troublesome interference Whose J frequency :depends 0111 the" tuning fre- ,tone.

. quency of the said oscillatory circuits; In-this 3:, Inorder that the invention may be clearly case the twoqauxiliary oscillationsarecompared, understood and readily'carried into effect, it will A with respect to their frequencies, in thefl'e- :nowbe described more fully with respectto the quency detector, while as the::result of this, comaccompanying drawing, which represents, by a parison the tuning frequency of thesaid Oscillaway of example,'one form of construction.

tol'y CirCuilJSiSbrOught n c er m ntvv h- 4'.) :Thedrawing represents a superheterodyne readjusted oscillator frequency. rceiver constructed forvremote control; .The re- T fi v y b applied 1 111018 'p ceiver is arranged at the point of reception A and larly to apparatus Whose "tunin --fr quency is a .is connected by-means of conductors to the rede edby the Sum the'idifferenceflf; the mote control means located at the point-ofconfrequencies of two or more "oscillators, one of trol B. a

whichis adjustable byxsteps and the, other. con- .The receiver comprises ahigh-frequency amtinuously. plifier I, a mixing stage 2, an intermediatevIn 'this'casethe-remote control-is efi'ected, in frequency amplifier 3 and a detector and lowaccordancewith thesinvention insuchmanner frequency amplification, stage 4. The amplified that the oscillator adjustable by steps is arranged 50 low-frequency oscillations are supplied, through near the apparatus and is zcontrolledxfrom, the A the intermediary ,of-, a conductor 5, to, a loudrremote point of control and the continuously speaker 6,,which-isarranged'at the point of conadjustable oscillator is-arranged at thepoint of trol B. control and is directlyadjustedatthis point. The local oscillations for. the receiven are m-Suchsan apparatusais preferably constructed in =6 lformedain the-mixing stage Ito which are supplied both the oscillations of a continuously variable oscillator 8 (located at the point of control B and controlled there) and the oscillations of the stepwise adjustable oscillator 9 (located near the receiver). The oscillator 9 is adjusted from a distance in a manner known in itself; the device used for this purpose is denoted in the drawing by H] and is connected to a mixing stage 1 by means of a conductor [2.

The oscillations obtained by mixing in the mixing stage I are supplied to the mixing stage 2 where they act as local oscillations. Let us-assume that the receiver is intended for receiving a frequency range of from 3 to- 12 mc./s. and that the intermediate frequency is 400 kc ./s. The local oscillations must in this case be variable through a range of from 3.4 to 12.4 mc./s. This may be achieved, for example, by making the oscillator 9 adjustable by steps to the frequencies 3, 4 9, 10 mc./s. and by making the oscillator 8 continuously adjustable through a frequency band of from 1.4 to 2.4 mc./s. By combining each time a selected frequency of the oscillator 9 with the frequency band of the oscillator 8, it is possible to cover the whole range in which the local oscillations must be varied.

Since the frequency of the local oscillations is directly related to the tuning frequency of the oscillator 9, the receiver is tuned at the same moment at which the member for the remote control of the fine adjustment (in the present case the tuning condenser of the oscillator 8) is adjusted. Consequently there does not occur a troublesome delay between the tuning of the apparatus and the adjustment of the remote control device.

The tuning of the oscillatory circuits pertaining to the high-frequency portion of the receiver is effected with the aid of a generator 13 which generates a second auxiliary oscillation whose frequency depends on the tuning frequency of these oscillatory circuits. To that end the tuning condenser of the generator I3 is mechanically coupled to the tuning condensers of the said highfrequency portion. The local oscillations themselves are utilized as the first auxiliary oscillation. The second auxiliary oscillation and the local oscillations are both supplied to a frequency detector I4. From this frequency-detector I4 is taken a control voltage which energizes a relay l5. This relay actuates a motor l6 which is coupled to the tuning condensers of the high-frequency portion and to the tuning condenser of the generator IS. The motor moves the tuning condensers until the frequencies of the second auxiliary oscillation and of the local oscillations are equal. When this equality is attained the relay l and the motor I6 are switched off. Since in the example given the local oscillations vary from 3.4 to 12.4 mc./s., the frequency of the generator Is also varies from 3.4 to 12.4 mc./s. The

tuning of the high-frequency circuits covers in this case the frequency range of from 3 to 12 mc./s.

As a rule such a range cannot be covered without switching-over the fixed reactances pertaining to the oscillatory circuits of the high-frequem cy portion and of the generator l3.

Let us assume that the whole range of the high-frequency portion, which extends from 3 to 12 mc./s., is subdivided into three bands: 3-6, 6-9 and 9-12 mc./s.;..in this case the generator I3 is also switched-over three times: 3.4-6.4, 6.4-9.4 and 9.4-12.4 mc./s. The change-over switch of the high-frequency portion I is designated by I! and that of the generator [3 by [8. The changeover switches of the stepwise adjustable oscillator 9, of the high-frequency portionl and of the generator [3 are coupled to one another and this in such manner that to a number of steps of the oscillator 9 always corresponds the same position of the change-over switches I! and 18, for example: to the frequencies 2, 3 and 4 mc./s. of the oscillator 9 correspond the band of from 3 to 6 mc./s. of the high-frequency portion 1 and the band of from 3.4 to 6.4 mc./s. of the generator I3, and so forth. Now the tuning condensers of the high-frequency portion I and of the generator 13 pass once through their whole range in the period of time in which the tuning condenser of the oscillator 8 passes three times through its range;

It is not always desirable to compare the oscillations of the generator l3 and the local oscillations with respect to equality, for if the frequency of the generator 13 does not become exactly equal to the frequency of the local oscillations, disturbances may arise under certain conditions due to interference between the said oscillations. This is the reason why it is sometimes .preferred to compare the two oscillations with respect to a fixed differential frequency, said frequency being so chosen that any interference frequency which may occur does not have a detrimental effect on the operation of the apparatus. In the present case, this differential frequency may, for example, be taken larger than the intermediate-frequency bandwidth. This must, of course, be taken into account when constructing the generator [3.

What we claim is: l. A remotely controlled frequency converting system comprising a radio frequency amplifier provided with continuous tuning means. a heterodyne circuit arranged to mix the output wave of said amplifier with local oscillations, a source of local oscillations for said heterodyne circuit providedwith a remotely positioned control oscil lator continuously tunable within a predetermined range and arranged to vary the frequency of said source of local oscillations, an auxiliary oscillator continuously tunable within a predetermined range, the tuning means of said amplifier being coupled for movement in accordance with the tuning of said auxiliary oscillator, means to compare the frequencies of said source and said auxiliary oscillator to develop a control voltage whose value depends on the frequency difference therebetween, and motive means responsive to said control voltage and coupled to tune said auxiliary oscillator to maintain a predetermined fremotely positioned control oscillator continuously tunable within a. predetermined range and a mixer for combining the frequencies of said generator and said control oscillator to produce local oscillations Whose frequency is varied by the adjustment of said control oscillator, an auxiliary oscillator continuously tunable within a predeter mined range, the tuning means of said amplifier being coupled for movement in accordance with the tuning of said auxiliary oscillator, means to compare the frequencies of said source and said auxiliary oscillators to develop a control voltage whose value depends on the frequency difference therebetween, and motive means responsive to said control voltage and coupled to tune said auxiliary oscillator to maintain a predetermined frequency relation between said auxiliary oscillator and said source, thereby effecting tracking be,- tween said source of local oscillations and the tuning of said amplifier.

3. A remotely controlled superheterodyne re-' ceiver comprising a radio frequency amplifier provided with tuning means, a heterodyne circuit arranged to mix the output Wave of said 'amplifier with local oscillations to produce an intermediate frequency signal, a source of local oscillations for said heterodyne circuit provided with al remotely positioned control oscillator continuously tunable within a predetermined range and arranged to vary the frequency of said source of local oscillations, an auxiliary oscillator continuously tunable within a predetermined range, the tuning means of said amplifier being coupled for movement in accordance with the adjustment of said auxiliary oscillator, a frequency discriminator electrically coupled to said source and auxiliary oscillator to produce a control voltage whose value depends on the frequency difference therebetween, a motor arranged to adjust said auxiliary oscillator, and relay means responsive to said control voltage to effect energization of said motor in a direction maintaining synchronism between the frequencies of said source and said auxiliary oscillator, thereby effecting tracking between said source and the tuning of said amplifier.

4. A remotely controlled frequency converting system comprising a radio frequency amplifier provided with tuning means and a step-wise band switching mechanism, a heterodyne circuit arranged to mix the output Wave of said amplifier with local oscillations, a source of local oscillations including a generator for producing oscillations and adjustable in frequency in a step-wise manner, a remotely positioned control oscillator continuously tunable within a predetermined range and a mixer for combining the output of said control oscillator and said generator to produce local oscillations for said heterodyne circuit, Y

an auxiliary oscillator provided with a step-wise band switching mechanism and means to tune continuously throughout each band, the tuning means of said amplifier being coupled for movement with the tuning means of said auxiliary oscillator, a remotely positioned control device for simultaneously operating the step-Wise adjustment means of said amplifier, said auxiliary oscillator and said generator, means to compare the frequencies of said source and said auxiliary oscillator to produce a control voltage Whose value depends on the frequency difference therebetween, and motive means responsive to said control voltage and coupled to the continuous tuning means of said auxiliary oscillator to maintain a predetermined relation between said auxiliary oscillator and said source.

HERMAN BERNARD RUDOLF BOOSMAN.

EDUARD HERMAN HUGENHOLTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS I Great Britain May 29, 1940 

